US4230180A - Isolating packer units in geological and geophysical measuring casings - Google Patents

Abstract

The isolating packer unit is made up of a cylindrical measuring casing one end of which is connected by a cylindrical coupler tube to an end of a similar measuring casing, this coupler tube having a measuring port normally closed by a valve which is operable from within the tube to open the port. An elongate elastic packer tube is mounted on and concentric with each casing and is secured at its ends to the casing. When the packer unit is in a well or bore hole, the packer tubes are expanded or inflated by fluid directed thereinto to engage the wall of the well or bore hole to isolate the measuring port of the coupler tube from the portions of the well or bore hole above and below the packer unit.

Description

FIELD OF THE INVENTION

This invention relates to isolating packer units in geological and geophysical measuring casing assemblies which are inserted in wells or bore holes so that instruments such as probes can be moved through the casing assemblies to take measurements and/or samples.

DESCRIPTION OF THE PRIOR ART

It is common for internally grooved casings to be placed in wells or drill holes to permit an inclinometer to be inserted inside the casing to measure the inclination of the casing at various depths and at different times. Movement of the surrounding soil or rock can be inferred by noting changes in the inclination of the casing between successive readings. However, the existing inclinometer casings are not suitable for making numerous piezometric measurements to establish and monitor the distribution of fluid or gas pressure on the exterior walls of the casing. Occasionally, the bottoms of existing types of inclinometer casing can be left open so that they can be used to measure fluid or gas pressure and to take samples at a single point. However, even in this case it is difficult to ensure that a positive hydraulic seal has been made on the exterior of the casing to ensure the necessary hydraulic isolation of the measuring point. Furthermore, it has been practically impossible to achieve a positive mechanical coupling between the soil or rock in the walls of drill holes and inclinometer casings where adverse field conditions exist, for example, where the drill hole intersects large voids or where the casing must be installed at great depths.

It is also common for one or two piezometric (fluid or gass pressure) measurements to be made in a single well and occasionally as many as four different locations are monitored in a single well. However, in these cases separate casings or individual hydraulic or pneumatic tubing are required to reach each piezometer location and there is a practical limit to about three or four installations that can be successfully placed in a single well. A common limiting factor is the inability of the prior methods to successfully isolate a large number of piezometric measurement locations from each other. Another current method of making several piezometer measurements in a single well is to install electrical or electronic devices in the well. However, there is a practical limit to the number of such devices that can be successfully installed and sealed in a well and these devices are every susceptible to errors during longterm monitoring programs as moisture seals tend to leak disturbing the electric or electronic circuitry. These devices are also susceptible to damage from lightning discharges. Existing pneumatic and electrical or electronic devices cannot easily be checked or recalibrated following installation. Thus, the quality of their data cannot be verified.

When currently available pneumatic, electrical and electronic piezometers are sealed in a well, fluid or gas samples cannot be taken. Therefore, another well must be drilled for fluid or gas sampling. Fluid or gas samples are often taken in wells for analysis of the quality or chemical composition. However, methods of sampling do not permit a high density of sampling points down a well. Furthermore, it has been possible to hydraulically seal the sampling points from each other.

It is important in the sampling of fluids in a well that the method of isolating the sampling points does not contaminate the fluid or gases which are being sampled. Thus, the sampling tool, sampling points and sealing methods should have a negligible effect on the existing hydrologic environment during installation and the sampling process.

SUMMARY OF THE INVENTION

The present packer units form part of a casing assembly that may extend from the top to the bottom of a well or bore hole. These units make it possible to take measurements or samples at as many different levels in the well or bore hole as practical without each measurement or sample being contaminated by conditions at the other levels. The packer units permit positive mechanical coupling with the soil or rock of the drill hole even under adverse field conditions, thereby providing hydraulic isolation of the measurement or sample points from each other. The measurements or samples are taken at the desired levels through measuring ports in couplers forming part of the casing assembly at said levels. Each packer unit includes one of these couplers, and casings of the assembly above and below the coupler in axial alignment therewith. An elastic packer tube or bag mounted on and concentric with each of said casings is inflatable from the top of the well or bore hole to engage the sides thereof and thereby seal and isolate the measuring port from areas of the well or bore hole above and below the packer unit. Thus pressure and temperature measurements or fluid samples, for example, can be taken at the different levels without the danger of being affected by temperatures, pressures and fluids at other levels. Thus, each measuring port is isolated from all of the other measuring ports of the casing assembly.

This apparatus is very simple in construction and easy to operate from above the well or bore holes. It can very readily be put into operative position within a well or bore hole, and the measuring ports quickly and easily isolated from each other.

An isolating packer unit in accordance with this invention comprises axially aligned and spaced measuring casings through which can be moved instruments or probes for taking measurements and samples in wells or bore holes, a coupler tube connected at opposite ends to ends of the casings, said casings and tube forming a common passageway through which instruments or probes can be moved to take measurements and samples, a measuring port in the coupler tube permitting communication between the interior and exterior thereof, a valve normally closing the measuring port and operable from within the tube to open said port, an elongate elastic packer tube mounted on and concentric with each casing, said each casing extending through its packer tube and beyond the ends thereof, securing means fastening the ends of each packer tube to the casing extending through the latter packer tube, and means for directing fluid from the top of the well or bore hole in which the packer unit is located into both of said packer tubes to expand the packer tubes to engage the wall of said well or bore hole to isolate the measuring port of the coupler tube from the portions of the well or bore hole above and below the packer unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Isolating packer units in accordance with this invention are illustrated by way of example in the accompanying drawings, in which

FIG. 1 diagrammatically illustrates a packer unit in a well or bore hole,

FIG. 2 is an enlarged longitudinal section of one form of packer tube in the collapsed condition.

FIG. 3 is a view similar to FIG. 2 showing the packer tube in the inflated and sealing condition,

FIG. 4 is a vertical section view through the coupler of this packer unit,

FIG. 4A is a fragmentary sectional view illustrating an alternative form of sealing connecting means between a coupler and a casing,

FIG. 5 is a vertical section through the coupler taken at right angles to FIG. 4,

FIG. 6 is a diagrammatic elevation of a probe that can be used in this apparatus,

FIG. 7 is an elevation of the probe at right angles of FIG. 6,

FIG. 8 is a vertical section through an alternative form of packer tube,

FIG. 9 is a horizontal section taken on the line 9--9 of FIG. 8,

FIG. 10 is an enlarged perspective view of a protective insert of the packer tube of FIG. 8,

FIG. 11 is a vertical section through another alternative form of packer tube, and

FIG. 12 is a vertical section through a further alternative form of packer tube.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 of the drawings, 10 is a well or bore hole, and 11 is a geology or geophysical casing assembly made up of a plurality ofpacker units 12, each of said units comprising twopackers 15 interconnected by acoupler 18. Thepackers 15 includeelongate casings 20 which are illustrated at adjacent ends by said couplers to form apassageway 22 extending longitudinally through the casing assembly.

In this example, thecasing 20 of eachpacker 15 extends through and is substantially concentric with an expandable cylindrical packer tube, membrane orbag 25 formed of suitable elastic or stretchable material, such as natural or synthetic rubber or a plastic such as urethane. Urethane is preferable for this purpose because it is readily moldable, and has high strength and abrasion characteristics when expanded. The packer tube is clamped at opposite ends ofcasing 20 by circular fasteners orclamps 28. The ends ofcasing 20 project beyond the ends of thepacker tube 25.

As the packer tube is molded, it is preferable to mold it so that theends portions 30 are thicker than thecentral section 31 extending therebetween. The thicker portions are located at points where the packer tube is subjected to the greatest strain, while the thinner central section will readily fit against the irregular surface of thewell 10 to form a fluid-tight seal.

In this example, theelastic tube 25 of thepacker 15 is inflated through aninflating port 32 incasing 20 of said packer and normally is closed by a suitable check valve which opens outwardly therefrom. In this example, the check valve is in the form of a relatively wideelastic band 33 which fits aroundcasing 15 within bag ortube 25 and over the inflating port. FIG. 2 shows the check valve orband 33 in the closed position, and FIG. 3 shows the valve or band in the open position. When pressure is exerted radially throughport 32, the adjacent edge ofband 33 is forced outwardly to open the port. When the pressure within bag ortube 25 exceeds pressure withincasing 20, thecheck valve 33 will close and remain closed.

An example of acoupler 18 for apacker unit 12 is illustrated in FIGS. 4 and 5. This coupler is in the form of atube 35 formed of plastic, metal or the like. The ends 37 of the tube are open and haveannular enlargements 38 therein and opening outwardly therefrom for receiving the ends ofcasings 20. If desired, this arrangement can be reversed, that is, the ends of the coupler tube may be of such size as to fit into the ends of the casings. The interior ofbore 39 of thecentral section 40 oftube 35 is axially aligned with and of the same diameter as the interior ofbore 42 of thecasings 20. It is to be understood that any suitable type of coupler may be used in place ofcoupler 18.

Suitable connecting and sealing means is provided between each end of the coupler tube and the adjacent end of a casing. In this example, sealing connecting means is provided in theenlargement 38 of eachend 37 of the coupler tube. This sealing connecting means includes anannular groove 45 in the inner surface of the coupler tube and containing a sealingring 46 therein. As an alternative, saidgroove 45 may be replaced by agroove 47 in the outer surface ofcasing 20, in whichcase sealing ring 46 is located in thisgroove 47, as shown in FIG. 4A. This ring receives and fits tightly around the end of casing 20 withinenlargement 38. Thegroove 45 is spaced inwardly from the adjacent end oftube 35. Anotherannular groove 49 is formed in the inner surface oftube 35 betweengroove 45 and the adjacent tube end, groove 45 overlying and registering with a similarannular groove 50 formed in the outer surface of the end ofcasing 20. Anorifice 52 extends through the wall oftube 35 and opens into thegroove 49 thereof, see FIG. 4. Aflexible shear fastener 54 extends through the registeringannular grooves 49 and 50 to lockcoupler 18 andcasing 20 together. This cord is insertable into the registering grooves throughorifice 52, and can be moved through said orifice. The fastener may be in the form of a flexible wire, strand or cord which is strong enough to prevent relative longitudinal movement between the coupler tube and the casing. Any other suitable connecting and sealing means may be used, such as normal male and female pipe threads and gaskets between each end of the coupler tube and the adjacent casing.

A measuringport 58 is formed in the wall ofcoupler tube 35 spaced from the ends of said tube. This port is normally closed by a suitable valve which can be opened from within the tube. An example of a valve suitable for this purpose is shown in FIGS. 4 and 5.

Avalve 60 having a seal in the form of an O-ring 61 is seated inport 58 and has astem 62 extending through the port and slightly into thebore 39 oftube 35. This stem preferably has arounded end 64. Suitable means is provided for normally retainingvalve 60 in the closed position, and in this example, anelastic pad 67 presses against the valve to retain the latter seated in and closingport 58. The method of retaining this pad in position will hereinafter appear.

Port 58 is provided to enable measurements, such as pressure and temperature measurements, to be taken in thearea surrounding coupler 18 withinbore hole 10 and betweenpackers 15. Samples of gases or liquids in the bore hole and/or of the material in which the bore hole is formed can also be taken in throughport 58.

As it is desirable in most cases to protect the port and valve as much as possible from particles of dirt, a shield in the form ofwide band 70 can extend around the outer surface ofcoupler tube 35 and preferably fits in a wideannular groove 71 formed in the outer surface of the tube and overlying but spaced fromvalve 60. By referring to FIG. 4 it will be seen that thegroove 71 overlies anotherannular groove 73 which is formed in and extends around the outer surface of the coupler tube, saidgroove 73 being narrower thangroove 71 so as to formannular shoulders 74 on whichband 70 seats. A pair of spacedribs 76 and 77 project upwardly from the bottom ofgroove 73 and form a groove orpassage 78 therebetween. It will be noted thatvalve 60 andelastic pad 67 are located withinpassage 78 ofgroove 73 beneathcover band 70 and that said cover band retains the pad in position on the valve. Theribs 76 and 77support cover band 70 against external pressure and keep it clear ofvalve 60.

Cover band 70 is formed with a relativelylarge opening 79 therein, this opening preferably being spaced away fromport 58, and in this example is on the opposite side oftube 35 from the port. Thepassage 78 betweenribs 76 and 77 extends in opposite directions from band opening 79 toport 58. If desired, this passage can be filled with asuitable filter material 81 which prevents particles from travelling to the port and its valve. In addition, shortannular ribs 83 may be formed on and project outwardly from the bottom of space orpassageway 78 within thecover band opening 79. These ribs havespaces 84 therebetween, some of which are located inpassage 78. Thespaces 84 located inpassage 78 are in communication at opposite ends thereof with the passage. Theseribs 83 help prevent theopening 79 from being clogged with dirt.

FIGS. 6 and 7 illustrate an example of a probe orinstrument 90 that can be used with thecasing assembly 11. This probe is in the form of an elongatecylindrical casing 91 having a raised or ported face plate orsurface 92 facing laterally therefrom, said face plate having a circular andresilient ring seal 93 thereon and projecting therefrom. Aport 94 is located inface plate 92 withinring seal 93 and communicates with the interior of the probe. On the opposite side of the bore casing is an operating plate orshoe 95 which is normally retracted but which can be moved a little outwardly in the radial direction. The probe casing also has an outwardly and downwardly extendingstop arm 97 radiating therefrom. Although this arm may be fixed, it is preferably retractable into the casing. In addition, the stop arm preferably is depressible when the probe is being moved upwardly, but not when the probe moves downwardly. Acable 98 is connected to the upper end ofprobe 90 by means of which the latter can be lowered through thepassageway 22 incasing assembly 11 and drawn upwardly therethrough. This probe contains whatever mechanisms are necessary to make geophysical measurements, such as to measure temperatures, pressures and the like and to take samples of gas, liquid or particulate material. It also includes the necessary mechanism and controls for extending and retractingoperating plate 95 and stoparm 97. The hydraulic, pneumatic or electrical connections for the probe are within or extend along the side ofcable 98. As this probe does not form a part of the present invention, it is not necessary to describe herein the various mechanisms thereof.

Suitable stop means is provided oncoupler tube 35 so positioned relative to measuringport 58 as to stopprobe 90 in the tube in correct operating position at the measuring port for taking measurements and samples through said port. Incoupler 18, this stop means comprises a pair ofhelical shoulders 105 on the inner surface of the wall oftube 35 and curving away from each other from adjacent outer ends 106 inwardly of the tube and back to adjacent inner ends 107 on the opposite side of the tube from said outer ends. Astop surface 109 is formed on the inner surface of the coupler tube at the inner ends 107 ofhelical shoulders 105.

Whenprobe 90 moves downwardly through thepassageway 22 into thetube 35 ofprobe 18, the projectingstop arm 97 of the probe engages a portion of one of theshoulders 105. As the probe continues to move downwardly, the stop arm rides on the shoulder with which it is in engagement and is rotated and guided on to thestop surface 109. The helical surfaces and the stop surface are so located that when the stop arm of the probe is located on the stop surface, the probe is in correct operating position both longitudinally and circumferentially at measuringport 58. With the illustratedprobe 90, theface plate 92 thereof with the ports therein isopposite port 58 at this time, and theseal ring 93 surrounds said measuring port. When operatingplate 95 is moved outwardly, it engages the wall ofcoupler tube 35 at a point opposite the measuring port, and this shifts theprobe 90 laterally untilseal 93 engages the inner wall of the tube around the measuring port to isolate the latter from the rest of the interior of the coupler tube. At the same time,face plate 92 presses againststem 62 to liftvalve 70 off its seal. The probe can now be operated to take the desired measurements or samples.

Two of thepackers 25 and the coupler therebetween constitute an isolatingpacker unit 12 embodying this invention, as shown in FIG. 1. As there are a plurality of these packer units in succession in the well 10, thepacker 25 at the lower end of one isolating unit may serve as the packer at the upper end of the next isolating unit down the well. However, if it is desired to take measurements or samples from relatively small isolated areas spaced some distance from each other, then each of the isolating packer units may have its own upper and lower packers.

The geological and geophysical measuringcasing assembly 11 is made up of thepackers 25 and theircouplers 18 which are secured together to build up said assembly as the latter is lowered intowell 10. The bags ortubes 25 of the packers are deflated at this time. Once the assembly is in position, a suitable fluid, such as air or water, is directed through the inflatingports 32 to inflate or expand the packer tubes orbags 25 until they fit snuggly against the wall of the well. Inflation pressures appreciable in excess of the natural fluid or gas pressures are commonly used to ensure a good seal between thebags 25 and the walls of the well. If the bottom of the casing assembly is closed, the inflating fluid can be directed down through thepassageway 22 therein with sufficient pressure to open thecheck valves 33 and to inflate the packer bags or tubes. However, a preferred way is to direct the inflating fluid into each inflating port on its own. This may be accomplished by a conventional or modifieddrill rod 115 having a conventional or modified double-packer arrangement 116 near its lower end (see FIG. 3). This arrangement has upper andlower packers 118 and 119 of such size as to slidably fit withincasing 20. Thepacker arrangement 116 also has one ormore orifices 120 formed inrod 115 between thepackers 118 and 119. The lower end ofrod 115 is formed with a reducedportion 121 upon which asleeve 122 is mounted for limited vertical movement. Astop arm 123 swingably mounted within a slot in theend portion 121 can be swung outwardly to a downwardly-inclined position by a biasingspring 124. Whensleeve 122 is in a normal lower position, it retainsarm 123 retracted in its slot, and when said sleeve is moved upwardly, aslot 125 therein registers with the stop arm, thereby allowing said arm to swing outwardly.

In order to move thepacker arrangement 116 into operative position, it is moved downwardly throughcasing passageway 22 untilsleeve 122 engages the bottom of the well. This action results insleeve 122 being moved upwardly to allowstop arm 123 to swing outwardly. Thenrod 115 is drawn upwardly until the packer arrangement is in thepacker 15 at the desired level, following which the rod is lowered untilarm 123 engages thestop 109 in thecoupler 18 below said packer. The stop arm and saidcoupling stop 109 are so located relative to the inflatingport 32 of theadjacent packer 15 that thepackers 118 and 119 are above and below said port and thepacker arrangement orifices 120 are substantially aligned therewith.

When the fluid is pumped downrod 115 with thepacker unit 116 in the position shown in FIG. 3, the fluid emerges throughorifices 120 and passes throughport 32, the pressure of thefluid forcing valve 33 to the open position.

If permanent seals are desired, the deflated packer tubes orbags 25 may have cement, grout or gel therein which hardens or sets when mixed with water. In this case, water would be pumped down through therod 115 and into the packer bag or tube to inflate the latter and to moisten the material therein eventually hardens or sets to form a permanent seal. Alternatively, cement, grout or gel may be pumped from the surface intobags 25 through tube ordrill rod 115.

Each isolatingpacker unit 12 makes it possible to take measurements or samples from a given area in well 10 without fear of contamination from gases or chemicals from other levels within the well. These isolating units are very simple in construction and are very easy to install. Any desired number of these isolating units may be connected together to operate in wells or drill holes of any depths.

FIGS. 8, 9 and 10 illustrate a packer 15a for the isolating packer units and having an alternative means for directing fluid into the packer tube orbag 25 thereof. In this example, the inflatingport 32 and itscheck valve 33 are omitted, and apipe 126 extends into the upper end ofpacker tube 25, this pipe having acoupler 127 on its outer end. Anothershort pipe 129 extends into thepacker tube 25 at its lower end, and has acoupler 130 on its outer end. Thepipes 126 and 129 extend into the packer tube beneath theclamps 28. Suitable means is provided for providing a fluid-tight seal at these points. In this example, each of thepipes 126 and 129 is molded into and extends through aprotective insert 135, shown in FIG. 10. This insert is formed of a relatively soft sealing composition such as urethane. Each pipe is molded in and extends through itsinsert 135. The insert preferably has aninner surface 137 shaped to fit around the surface of acasing 20, and an outercurved surface 139 which tapers laterally to form very thin side edges 140 of the insert. With this arrangement, the insert is relatively thick in the longitudinal center thereof, see FIG. 10, and tapers to its side edges 140. Thepipe 126 or 129 extends through the thick middle of the insert.

Thelower pipe 129 of each packer is connected to theupper pipe 126 of the packer immediately below it. Thelower pipe 129 of the last packer in the series within the well is closed by a suitable plug, while theupper pipe 126 of the uppermost packer is connected to ahose 145 leading to the top of the well and to a source of pressurized fluid for inflating the packer tubes.

The packers 15a operate as described above, excepting that theirrespective packer tubes 25 are inflated by fluids directed thereinto through thepipes 126. The fluid is pumped at a suitable pressure until all of these packer tubes or bags are completely inflated to seal off the spaces between therespective packers 15 of thepacker unit 12.

FIG. 11 illustrates apacker 15b of an isolating packer unit having an alernative method of sealing thepipes 126 and 129 in the upper and lower ends of the packer tube orbag 25. As the packer tube or bag is formed of moldable material, thepipes 126 and 129 are molded in the ends of the tube or bag when the latter is formed. Thepipes 126 and 129 extend through the ends and open into the interior of the packer tube or bag.

The packers of this embodiment of the invention are inflated in the manner described in connection with the alternative of FIGS. 8, 9 and 10.

FIG. 12 illustrates a packer 15c incorporating another alternative method of connecting thepipe 126 and 129 to the packer tubes orbags 25. In this example, apacker head 145 is provided for each of these pipes. Each packer head is formed of moldable material such as urethane and is formed with acentral bore 147 which fits tightly oncasing 20. The packer head has anannular notch 148 in its inner end into which the adjacent end of a packer tube orbag 25 fits, said packer tube being secured in position on the head by theclamp 28. An internalannular groove 150 is formed in the packer head and has a suitable seal therein, such an O-ring 151 which is pressed against the outer surface ofcasing 20. Thepipe 126 or 129 is molded inhead 145 and extends from the outer end thereof into thebore 147. Anaxial slot 155 is formed in the bore surface ofhead 145 and opens out therefrom at theinner end 156 of the head.

With the arrangement of FIG. 12, fluid is pumped into thepacker tube 25 throughpipe 126. This fluid travels through the pipe into theaxial slot 155 of theupper head 145 and then into the interior of the packer tube or bag. If the illustrated packer is connected to the packer therebelow, fluid travels through theslot 155 of thelower packer head 145 and throughpipe 129 into the upper packer of the next packer unit.

In order to take a measurement or sample at a desired level inbore hole 10 after thepackers 15 have been inflated, the probe orother instrument 90 is lowered with itsstop arm 97 retracted until the probe is just below the coupler located at the desired level. Then the probe is raised with the stop arm extended until the probe is a little above said coupler, and when the probe is lowered again, the stop arm is directed on to thestop surface 109 ofcoupler 18 to stop the probe in the correct operating position to take a measurement or sample at the desired level. As the probe is raised during this maneuver, the stop arm is depressed when it contacts valve stem 62 so as not to open thevalve 60 at this time.

Claims (11)

We claim:

1. An isolating packer unit in a geological and geophysical measuring casing made up of a plurality of said units at different levels and through which can be moved instruments for taking measurements and samples in wells or bore holes at said different levels, each isolating packer unit comprising:

axially aligned and spaced measuring casings,

a coupler tube connected at opposite ends to ends of the casings to interconnect the casings, said casings and tube forming a common passageway through which an instrument can be moved to take measurements and samples,

a measuring port in the coupler tube permitting communication between the interior and exterior thereof,

a valve normally closing the measuring port and operable from within the tube by said instrument to open said port,

an elongate elastic packer tube mounted on and concentric with each casing, said each casing extending through its packer tube and beyond the ends thereof,

securing means fastening the ends of each packer tube to the casing extending through the latter packing tube, and

means for directing fluid from the top of the wall or bore hole in which the packer unit is located into both of said packer tubes to expand the packer tubes to engage the wall of said well or bore hole to isolate the measuring port of the coupler tube from the portions of the well or bore hole above and below the packer units.

2. An isolating packer unit as claimed in claim 1 in which said fluid directing means comprises

an inflating port in each measuring casing, and

check valves normally closing the inflating ports, said check valves opening under pressure from within their respective casings.

3. An isolating packer unit as claimed in claim 2 in which each check valve comprises a wide elastic band fitting around the respective casing and overlying the inflating port of said respective casing.

4. An isolating packer unit as claimed in claim 1 in which said fluid directing means comprises

tubular means extending from the top of the wall or bore hole to said packer tubes and through which fluid can be directed thereinto to expand the packer tubes.

5. An isolating packer unit as claimed in claim 4 in which said tubular means comprises

a first pipe extending from and opening into one end of each of said packer tubes, and

a second pipe extending from and opening into the opposite end of each of said packer tubes, said pipes communicating with the interiors of their respective packer tubes, and each first pipe being adapted to be in communication with the top of the well or bore and each second pipe being adapted to be in communication with the first pipe of another packer tube.

6. An isolating packer unit as claimed in claim 5 in which the packer tubes are formed of moldable material, and each of said pipes extends through the material of its respective packer tube and is molded in said material.

7. An isolating packer unit as claimed in claim 5 in which an end of each of said pipes is molded into and extends through a protective insert formed of moldable material and fixed between an end of a packer tube and the casing to which said packer tube is secured.

8. An isolating packer unit as claimed in claim 7 in which each of said inserts has an inner surface shaped to fit around the surface of the casing, and an outer curved surface tapering laterally to form very thin side edges of the insert, whereby said insert is relatively thick in the longitudinal middle thereof and tapers to its side edges, the pipe of said insert extending through the thick middle thereof.

9. An isolating packer tube as claimed in claim 5 comprising;

a packer head for each of said pipes and fitting between an adjacent end of the packer tube and the casing thereof, each packer head having an axial bore into which an end of the casing tightly fits, said each pipe of the head being molded therein to open out in communication with the interior of the packer tube.

10. An isolating packer tube as claimed in claim 9 in which each of said packer heads has an axial groove formed in the wall of the bore thereof, said groove opening into the adjacent packer tube through an inner end of the head and said each pipe opening into said groove, and including a sealing ring in the packer head fitting tightly around the casing, said sealing ring being located between said groove and an outer end of the head.

11. An isolating packer unit as claimed in claim 1 in which the packer tubes are formed of moldable material, and the wall of each packer tube is thicker at each end thereof than in the center section between said ends.

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